The present invention relates to peptides which have immunomodulatory activity. More specifically, it relates to analogs of tuftsin.
An enormous number of factors are undoubtedly involved in vivo in the regulation of the immune system, and also in the growth and differentiation of normal and tumor cells. Tuftsin is one such natural immunomodulating factor, and its chemical structure has been established to be L-Thr-L-Lys-L-Pro-L-Arg. Tuftsin has been found to have a number of interesting biological activities, such as antitumor, anti-infection, anti-AIDS and growth factor activities, and enhancement of the phagocytic and cytotoxic activities of leukocytes.
The biological activities of tuftsin have led researchers to attempt to find analogs which have improved activity in one or more respects. Unfortunately, such attempts have been largely unsuccessful. Most of the analogs synthesized either have not possessed the desired activity, or have been found to be competitive inhibitors of tuftsin.
Therefore, a need exists for tuftsin analogs which have advantages in biological activity or in other respects over tuftsin.